1. Field of the Invention
The present invention relates to glass having ultrafine particles of CuCl and/or CuBr precipitated therein and a process for its production.
2. Discussion of Background
Recently, it has been found that glass having ultrafine particles of semiconductor such as CdS or CdSe precipitated therein, which used to be employed as a yellow to red sharp cut colored glass filter, has high nonlinear optical properties. Accordingly, an attention has been drawn to such glass as a prospective nonlinear optical material for e.g. ultra-high speed optical switches or memories utilizing the generation of harmonic lights, the generation of phase conjugated lights or the light bistability. It is believed that such high nonlinear optical properties of the ultrafine particle-precipitated glass are attributable to quantum-confining effects such that excitons in the ultrafine semiconductor particles are three dimensionally confined by the deep potential created by the glass.
As such glass having ultrafine semiconductor particles precipitated therein, the above mentioned glass having ultrafine particles of CdS-CdSe system precipitated therein, is known.
On the other hand, it has recently been theoretically predicted that very high nonlinear optical effects can be obtained by forming CuCl into very fine particles. Further, glass having CuCl precipitated therein, has been reported before in USSR, but no details such as the composition of the glass have been disclosed.
The glass having ultrafine particles of CdS-CdSe system precipitated therein shows high nonlinear optical effects which have not been observed in conventional nonlinear optical materials. However, its properties are still inadequate for its use as the above mentioned nonlinear optical material for e.g. a ultra-high speed optical switch or a memory, and it has a problem that it is inoperable unless a laser beam source having a very high output is employed.
On the other hand, Japanese Examined Patent Publication No. 3464/1971 discloses ultraviolet ray-absorbing glass comprising from 40 to 70% by weight of SiO.sub.2, from 10 to 26% by weight of B.sub.2 O.sub.3, and from 4 to 26% by weight of Al.sub.2 O.sub.3 and from 3 to 25% by weight of R.sub.2 O and having CuCl or CuBr particles precipitated therein. However, such glass has a problem that it is thereby difficult to precipitate ultrafine particles of CuCl or CuBr.